SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a6f26e381fea3fe31c6b0751f46d2ad86c91abacd539f64ef38bbb5df437b1c3' 
  AND token = 'zlIFaX18wiohabe/aVFzneyAveK9jAjNhOJlEql36TQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}